A pulse oximetry screen is a noninvasive (and painless) test performed on all newborn babies to determine the level of oxygen in their blood. This test uses rays of light of different wavelengths to measure the percent of hemoglobin (the part of blood that carries oxygen) that is filled with oxygen. Normally, a newborn baby should have an oxygen saturation level that is greater than 95%. Screening using pulse oximetry can detect some infants with congenital heart disease who otherwise may go undetected for a while. There are some congenital heart defects that cause a newborn baby to have lower oxygen saturation in the blood after birth. It often can be difficult to determine if a baby has cyanosis (bluish discoloration of the skin due to poor oxygen content of the blood) just by looking at him or her after birth.

How Is a Pulse Oximetry Test Performed?

The pulse oximeter has a lighted probe that is temporarily attached to the baby’s finger, ear lobe, or foot. Once the baby’s finger is attached to the probe (usually by a sticker), the red light of the probe reads the amount of oxygen carried by the blood. The oxygen level is tested in both arms and both feet. In some kinds of congenital heart disease, the numbers can be different in the arms compared to the legs. It also helps to validate the test to do it in all of the extremities. The time required to complete this test is approximately 1 to 5 minutes.

Is Pulse Oximetry Testing Safe?

Yes. There are no known risks associated with pulse oximetry testing. This is not a blood test so it does not require a needle stick. There is no radiation involved with this test as well. It simply temporarily shines a light through the skin to test how much of the blood contains oxygen.

Why Is Pulse Oximetry Testing Important?

Some congenital heart defects do not show signs within the first days or even weeks of life. Sometimes babies with significant congenital heart disease may not have a murmur after birth. Therefore, some babies may not show signs of significant congenital heart disease until after they become very sick. If healthcare providers discover a heart problem before a baby becomes ill, then the baby will have a better chance to do well with any necessary surgeries or procedures. Early diagnosis of the heart problem may also prevent damage to other organs that may occur when a baby becomes sick due to congenital heart disease.

While pulse oximetry screening cannot rule out all forms of congenital heart disease, it is a good starting point for evaluating many serious types of congenital heart defects. In 2011, the U.S. Department of Health and Human Services recommended the pulse oximetry screening should be included in the routine evaluation that all newborn babies undergo before they are discharged from the hospital after birth. More and more states are adopting this test as a routine procedure to be done on all newborn babies before they go home from the hospital.